That's not really fair since the shell is an independent part of the system and could be swapped out for another implementation. Plus, it's not there just for the init system; it'd be there regardless of the init system. It's an already existing independent component, which is used for leverage.

Otherwise should we also count the C compiler, libc, all the CLI utilities and the kernel?

But here you go. Still smaller than systemd. Sysvinit needs a shell too...

    $ wc -l /usr/src/bin/ksh/*.[ch]
     127 /usr/src/bin/ksh/alloc.c
    1412 /usr/src/bin/ksh/c_ksh.c
     935 /usr/src/bin/ksh/c_sh.c
     560 /usr/src/bin/ksh/c_test.c
      53 /usr/src/bin/ksh/c_test.h
     201 /usr/src/bin/ksh/c_ulimit.c
      60 /usr/src/bin/ksh/config.h
     829 /usr/src/bin/ksh/edit.c
      86 /usr/src/bin/ksh/edit.h
    2163 /usr/src/bin/ksh/emacs.c
    1333 /usr/src/bin/ksh/eval.c
    1433 /usr/src/bin/ksh/exec.c
     107 /usr/src/bin/ksh/expand.h
     593 /usr/src/bin/ksh/expr.c
     984 /usr/src/bin/ksh/history.c
     438 /usr/src/bin/ksh/io.c
    1653 /usr/src/bin/ksh/jobs.c
      13 /usr/src/bin/ksh/ksh_limval.h
    1643 /usr/src/bin/ksh/lex.c
     132 /usr/src/bin/ksh/lex.h
     196 /usr/src/bin/ksh/mail.c
     786 /usr/src/bin/ksh/main.c
    1149 /usr/src/bin/ksh/misc.c
      91 /usr/src/bin/ksh/mknod.c
     285 /usr/src/bin/ksh/path.c
     267 /usr/src/bin/ksh/proto.h
     420 /usr/src/bin/ksh/sh.h
    1161 /usr/src/bin/ksh/shf.c
      82 /usr/src/bin/ksh/shf.h
     897 /usr/src/bin/ksh/syn.c
     231 /usr/src/bin/ksh/table.c
     183 /usr/src/bin/ksh/table.h
     420 /usr/src/bin/ksh/trap.c
     708 /usr/src/bin/ksh/tree.c
     141 /usr/src/bin/ksh/tree.h
      57 /usr/src/bin/ksh/tty.c
      37 /usr/src/bin/ksh/tty.h
    1210 /usr/src/bin/ksh/var.c
      10 /usr/src/bin/ksh/version.c
    2128 /usr/src/bin/ksh/vi.c
   25214 total